swr: Refactor checks for compiler feature flags
Encapsulate the test for which flags are needed to get a compiler to
support certain features. Along with this, give various options to try
for AVX and AVX2 support. Ideally we want to use specific instruction
set feature flags, like -mavx2 for instance instead of -march=haswell,
but the flags required for certain compilers are different. This
allows, for AVX2 for instance, GCC to use -mavx2 -mfma -mbmi2 -mf16c
while the Intel compiler which doesn't support those flags can fall
back to using -march=core-avx2.
This addresses a bug where the Intel compiler will silently ignore the
AVX2 instruction feature flags and then potentially fail to build.
v2: Pass preprocessor-check argument as true-state instead of
false-state for clarity.
v3: Reduce AVX2 define test to just __AVX2__. Additional defines suchas
__FMA__, __BMI2__, and __F16C__ appear to be inconsistently defined
w.r.t thier availability.
v4: Fix C++11 flags being added globally and add more logic to
swr_require_cxx_feature_flags
Cc: <mesa-stable@lists.freedesktop.org>
Reviewed-by: Tim Rowley <timothy.o.rowley@intel.com>
Tested-by: Tim Rowley <timothy.o.rowley@Intel.com>
Signed-off-by: Chuck Atkins <chuck.atkins@kitware.com>
2 files changed